1. Field of the Invention
With reference to the classification of art as established in the U.S. Patent Office this invention pertains to a method as found in the general Class entitled, "Package Making" (Class 53) and in the subclass entitled, "cover adjunct application or formation" (subclass 47) and in the subclass entitled, "package opening device" (subclass 133).
2. Description of the Prior Art
The packaging of meat and other similar products where the product packaged is in the presence of a small vacuum is well known. In this packaging method the film or films are tightly drawn to the product and remain in a tightly sealed condition until the film is ruptured. Patents disclosing this method are well known. Such a package is found in U.S. Pat. No. 3,491,504 as issued on Jan. 27th, 1970 to W. E. Yound et al. In this and in other apparatus of a like nature the package is formed utilizing a bottom film which usually has thermoplastic characteristics. On this lower film is laid the product to be packaged and on top of the product in a vacuum chamber subsequently opened to atmosphere pressure the upper film is caused to be drawn tightly around the product and at this same time is sealed to the bottom film. Many packages are formed with a film having a good resistance to tear and accidental rupture since the products usually packaged may be subject to rather rough handling particularly under the influence of a substantially frozen or near frozen condition. Opening packages where there is a high resistance to tear usually requires an initial piercing by a sharp instrument. This is, of course, often an inconvenience.
Several patents have dealt with this problem and in particular is noted U.S. Pat. No. 3,184,051 to WINTON as issued on May 18th, 1965 wherein is shown a product wrapped with a tear tab and a strippable sheath. The tab provided with the wrapping of this product and as taught in the patent extends beyond the package films. Such a package, of course, is unacceptable for food and other items required to be protected by the seal of the film. In U.S. Pat. No. 1,722,086 to HAMMERLE as issued on July 23rd, 1929 there is shown a cigarette package wherein a serrated member is adapted to provide a cutting edge for the internal paper enclosing the cigarettes. In U.S. Pat. No. 3,187,983 to MENDOZA as issued on June 8th, 1965 there is disclosed a cellophane wrapper tearing member which is adhered to a carton. The sharp points of the tearing member are adapted to pierce the cellophane when the cellophane is pushed thereagainst. Once ruptured the cellophane is removed with little difficulty. A recent and important patent as to the use of a tear tab is seen in U.S. Pat. NO. 3,641,732 to FUJIO as issued on Feb. 15th, 1972. However, this package utilizes a heat shrink film and the tear tab portion consists of weakening the film itself prior to shipment which, of course, is not the desire of the present invention.
The present invention provides a method of encasing a tab having a projecting point which remains in a concealed condition until a corner of the package is deliberately bent into a folded U-shape and then pressing the film portion against the sharp point to cause a rupture of the film after which the film is torn with a pulling action to expose the product.